Method and device for vehicle-to-vehicle communication

ABSTRACT

A device and method for vehicle-to-vehicle communication. The method includes: a source device sends a request message to a base station, the request message being used for requesting the base station to allocating a resource; a node device that is synchronous with the source device sends synchronous information to at least one target device, so that the at least one target device establishes time synchronization with the source device according to the synchronous information, wherein the node device is a road-side device or an in-car device capable of communicating; the source device informs the at least one target device of a resource allocated by the base station; and the source device sends service information to the at least one target device by utilizing the resource.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15/769,954, filed Apr. 20, 2018, which is based on PCT filingPCT/CN2016/103182, filed Oct. 25, 2016, which claims priority to CN201510747096.2, filed Nov. 5, 2015, the entire contents of each areincorporated herein by reference.

FIELD

The present disclosure relates to a method and a device forvehicle-to-vehicle (V2V) communication, and in particular to a methodand a device capable of transmitting road safety information quickly andreliably.

BACKGROUND

Recently, V2V communication, which is mainly used for exchanging roadsafety-related information among vehicles, has been rapidly developed.For example, a vehicle can inform another vehicle of its own speed,position, driving direction, braking condition and the like. Therefore,a driver can be notified in advance through the V2V communication, forexample, by receiving warning information indicating that a distancebetween vehicles is too small or there is an accident ahead, such thatthe driver may have enough time to take actions, thereby reducingoccurrence of accidents.

Due to the characteristic of the V2V communication, there is a highdemand for rapid transmission of road safety information. Therefore, amethod for exchanging information among vehicles rapidly and reliably isrequired.

SUMMARY

In an aspect of the present disclosure, a device for vehicle-to-vehiclecommunication is provided, which includes one or more processorsconfigured to: perform control, in response to road event-relatedinformation from a source device, to establish time synchronization withthe source device; and generate synchronization information fortransmission to one or more target devices, so that the target devicesestablish time synchronization with the source device based on thesynchronization information, wherein the node device is a roadside unitor an onboard device capable of communication.

In another aspect of the present disclosure, a method for performingsynchronization in a vehicle-to-vehicle communication system isprovided, which includes: establishing, by a node device, timesynchronization with a source device, in response to road event-relatedinformation from the source device; transmitting, by the node device,synchronization information to one or more target devices; andestablishing, by the target devices, time synchronization with thesource device based on the received synchronization information, whereinthe node device is a roadside unit or an onboard device capable ofcommunication.

In another aspect of the present disclosure, a device forvehicle-to-vehicle communication is provided, which includes one or moreprocessors configured to: generate a request message for requesting abase station to allocate a resource; perform control to establish timesynchronization with a node device, such that at least one targetdevices establish time synchronization with the device based onsynchronization information transmitted by the node device, wherein thenode device is a roadside unit or an onboard device capable ofcommunication; generate a control message for informing the at least onetarget devices of the resource allocated by the base station; andgenerate service information related to a service for transmission tothe at least one target devices via the resource allocated by the basestation.

In another aspect of the present disclosure, a method for transmittingservice information in a vehicle-to-vehicle communication system, whichincludes: transmitting, by a source device, a request message to a basestation, wherein the request message is used for requesting the basestation to allocate a resource; transmitting, by a node device insynchronization with the source device, synchronization information toat least one target devices, such that the at least one target devicesestablish time synchronization with the source device based on thesynchronization information, wherein the node device is a roadside unitor an onboard device capable of communication; informing, by the sourcedevice, the at least one target devices of the resource allocated by thebase station; and transmitting, by the source device, the serviceinformation to the at least one target devices by using the resource.

In another aspect of the present disclosure, a method for transmittingservice information in a vehicle-to-vehicle communication system isprovided. The vehicle-to-vehicle communication system includes multiplebase stations, a controller for controlling the multiple base stations,a source device, and at least one target devices. The method includes:acquiring, by the controller, location information and serviceinformation of the source device from a serving base station of thesource device; transmitting, by the controller, the service informationto all neighbor base stations within a predetermined range around thesource device; and broadcasting, by each of the neighbor base stations,the service information to the target device within its coverage.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be better understood with reference to the detaileddescription given below in conjunction with the accompanying drawings.Identical or like reference signs denote identical or like componentsthroughout the accompanying drawings. The accompanying drawings togetherwith the following detailed description are incorporated into and form apart of the specification and serve to further illustrate the preferredembodiments of the disclosure and to explain the principle andadvantages of the disclosure by way of example. In the drawings:

FIG. 1 shows a scenario of LTE-based V2V communication.

FIG. 2 is a signal flow chart of transmission of road safety informationaccording to a first embodiment of the present disclosure.

FIG. 3 is a signal flow chart of a process when a terminal of a targetvehicle is out of synchronization.

FIG. 4 is a signal flow chart of a process of configuring an auxiliarynode device.

FIG. 5 is a signal flow chart of a process of acquiring a transmissionresource.

FIG. 6 schematically shows determination of a period for reporting ascheduling request based on priorities of services.

FIG. 7 is a flowchart showing an example of an interrupt processaccording to the present disclosure.

FIG. 8 is a signal flow chart of transmission of road safety informationaccording to a second embodiment of the present disclosure.

FIG. 9 is a block diagram showing an exemplary configuration of computerhardware.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a general scenario of LTE-based V2V communication. As shownin FIG. 1, it is assumed that a road accident, for example, a breakdownor a collision accident occurs to the source vehicle SV, around whichthere are a number of other vehicles (hereinafter referred to as targetvehicles DV) traveling. In this case, it is necessary to rapidlytransmit road safety information related to the road accident occurredto the source vehicle SV to the target vehicles DV in the vicinity, sothat drivers of the target vehicles DV can take actions in time, such asbraking or avoiding the source vehicle SV.

Specifically, in a practical scenario, communication terminals carriedby the source vehicle SV and the target vehicle DV are likely to beregistered with different operators. For example, as shown in FIG. 1,vehicle terminals of a source vehicle SV and target vehicles DV A areregistered with operator A, and vehicle terminals of target vehicles DVB are registered with operator B. FIG. 1 also shows two base stations A,B which are managed by the operators A and B, respectively. The vehiclesmay be within both the coverage of the base station A and the coverageof the base station B simultaneously.

FIG. 2 shows a signal flow chart of transmission of road safetyinformation according to a first embodiment. As shown in FIG. 2, theprocess includes four steps, each of which are described in detailbelow.

In a first step, after a road safety event occurs, the terminal of thesource vehicle SV generates road safety information and acquires atransmission resource for transmitting the road safety information froma serving base station of the source vehicle SV, as shown by step S210,which is described in detail below with reference to FIG. 5.

In a second step, the auxiliary node device AD synchronized with thesource vehicle SV transmits synchronization information to terminals ofmultiple target vehicles DV1 to DVn in step S220. In addition, in stepS230, the terminals of the target vehicles DV1 to DVn establish timesynchronization with the auxiliary node device AD based on thesynchronization information, thereby establishing synchronization withthe terminal of the source device SV (as indicated by the dotted line).For example, the auxiliary node device AD may be a roadside unit (RSU)or a vehicle terminal. The roadside unit is a device capable ofcommunication, and for example may be independently deployed on any sideof a road or installed together with a signal light. The vehicle canperform communication with the roadside unit when entering acommunication range of the roadside unit. For example, the roadside unitmay include a device that functions like a base station and a devicethat functions like a terminal. The roadside unit may be fixed ormobile.

In this present embodiment, the terminal of the auxiliary node device ADand the terminal of the source vehicle SV are registered with differentoperators, while the terminal of the auxiliary node device AD and theterminals of the target vehicles DV1 to DVn are registered with the sameoperator. In this case, the auxiliary node device AD may be insynchronization with the terminal of the source device SV according to aglobal synchronization signal source, which may include for exampleglobal navigation satellite system (GNSS) or a synchronization signalsource equivalent to GNSS, or may be a GNSS-based referencesynchronization signal source provided by a base station, and thepresent disclosure is not limited thereto. Therefore, as shown in FIG.2, the synchronization can be established between the terminals of thesource vehicle SV and the target vehicles DV1 to DVn registered withdifferent operators via the auxiliary node device AD, therebyfacilitating transmission of the road safety information.

It should be noted that the execution sequence of the first step and thesecond step is not limited to the above-mentioned. Instead, the firststep and the second step may be performed simultaneously or in an orderreverse to the above order depending on actual situation. For example,it is shown in FIG. 2 that step S210 is performed after step S220. Theexecution sequence of these two steps is not limited in the presentdisclosure.

In an example, a communication resource for transmitting synchronizationinformation may be indicated to the terminals of the auxiliary nodedevice AD and the target vehicle DV in advance. For example, in a casewhere the auxiliary node device AD is a terminal of a certain vehicle, aresource for transmitting synchronization information may be indicatedto the terminal of the vehicle and the terminal of the target vehicle DVin the system information block SIB 18 transmitted by the base station.Therefore, the terminals of the target vehicles DV1 to DVn can monitorthe resource to detect the synchronization information, and establishsynchronization based on the synchronization information.

The synchronization information may include a sidelink synchronizationsignal (SLSS) and a master information block-sidelink (MIB-SL).According to the conventional device to device (D2D) communicationtechnology, SLSS and MIB-SL are transmitted with a fixed periodicity of40 ms, and the occupied subframe is indicated by a parametersyncOffsetIndicator which is expressed as follows:(10*DFN+subframe number)mod 40=syncOffsetIndicator,where DFN is DirectFrame Number.

Considering sensitivity of the V2V communication to time delay, thetransmission period of SLSS and MIB-SL is shortened, for example, to 20ms or less in the present disclosure. Specifically, the auxiliary nodedevice AD may be configured, by a serving base station of the auxiliarynode device AD, with a relatively short transmission period for SLSS andMIB-SL, which is the shortest period that can be used by the auxiliarynode device AD for transmitting SLSS and MIB-SL. Specifically, in a casewhere the auxiliary node device AD is a roadside unit, the shortestperiod may be set for the auxiliary node device AD in advance. In thiscase, the auxiliary node device AD may determine a priority of theoccurred road event based on road event-related information from thesource vehicle SV, and transmit SLSS and MIB-SL with an appropriateperiodicity which is selected in a range greater than or equal to theshortest period based on the priority. For example, for a low-priorityevent, synchronization information is still transmitted with aperiodicity of 40 ms, and for a high-priority event, a periodicity of 20ms is used. Therefore, the parameter syncOffsetIndicator may beexpressed as follows:(10*DFN+subframe number)mod Factor_priority=syncOffsetIndicator,where Factor_priority may take a value of 40 (for a low-priority event),20 (for a high-priority event), or 10 (for emergency), and the like fordifferent road events.

In addition, in an example, the synchronization signal may betransmitted through dedicated signaling. For example, the identifier ofthe synchronization signal SSLS ID may be limited to a part of 167 IDsin the conventional D2D communication for distinguishing thesynchronization signal for the V2V communication from thesynchronization signal for the conventional D2D communication. Inaddition, in the conventional D2D communication, it is required that atransmitter notifies a receiver of information such as a network type(time division duplex or frequency division duplex) and a cyclic prefixtype (a normal or extended cyclic prefix) of a synchronization signal ineach transmission. In the present disclosure, the network type and/orthe cyclic prefix type of the synchronization signal may be prescribed.With the specific signaling as prescribed above, complexity in blinddetection of the synchronization signal by the terminal of the targetvehicle DV can be reduced.

In a third step, the source vehicle SV transmits control information tothe multiple target vehicles DV1 to DVn, as shown in step S240. Thecontrol information includes resource information for transmitting theroad safety information, a physical layer identifier (ID), a modulationand coding scheme, time calibration and the like. The resource fortransmitting the control information may be indicated in the MIB-SLtransmitted in the second step described above.

In a fourth step, the terminal of the source vehicle SV broadcasts theroad safety information to the multiple target vehicles DV1, DV2, . . ., DVn by using the transmission resource acquired from the base station,as shown in step S250.

Since the objects to which the road safety information is broadcastedare not fixed and are usually in great numbers, states of communicationchannels between the source vehicle SV and the multiple target vehiclesDV are uncertain each time the road safety information is broadcasted.However, high reliability is required in transmission of the road safetyinformation. In this case, the terminals of the source vehicle SV andthe target vehicles DV may operate in a fixed manner with respect to thephysical layer operation for the road safety information. In an example,the modulation and coding scheme for the road safety information may beprescribed in advance. Therefore, it is unnecessary for the sourcevehicle SV to additionally notify the target vehicles DV of themodulation and coding scheme at each broadcast, thereby facilitatingfast demodulation/decoding of the road safety information by theterminals of the target vehicles DV and saving overhead of controlinformation. In this example, the control information transmitted in theabove third step may not include the modulation and coding scheme.

The process where the terminal of the target vehicle DV is out ofsynchronization with the terminal of the auxiliary node device AD or theterminal of the source vehicle SV is described below with reference toFIG. 3. As shown in FIG. 3, the terminal of the target vehicle DV beingout of synchronization transmits a synchronization request to a servingbase station of the terminal of the target vehicle DV in step S310. Thesynchronization request includes location information of the terminalbeing out of synchronization.

The base station selects, based on the location information, anotherauxiliary node device AD which is adjacent to the terminal being out ofsynchronization and is in synchronization with the terminal of thesource vehicle SV, and instructs the new auxiliary node device AD to actas a synchronization source to transmit the synchronization informationto the vehicle being out of synchronization, as shown in step S320. Theresource for transmitting the synchronization information are indicatedto the terminal being out of synchronization and the selected auxiliarynode device AD by the base station through SIB 18.

Next, the vehicle being out of synchronization monitors the resourcewhich is used for transmitting the synchronization information and isprescribed by the SIB 18 in step S330, and re-establishessynchronization on detection of the synchronization information from theauxiliary node device AD.

The method for configuring the auxiliary node device AD is describedbelow with reference to FIG. 4. As shown in FIG. 4, after a road eventoccurs to the source vehicle SV, the source vehicle SV requests theserving base station A of the source device SV to allocate acommunication resource and reports its own location information and roadevent-related information (such as priority of the road event) in stepS410. Upon receiving the request along with the related information, thebase station A responds to the source vehicle SV (which is describedbelow in conjunction with FIG. 5) and notifies neighbor base stations ofthe position information of the source vehicle SC and the roadevent-related information in step S420. The neighbor base stations mayinclude base stations belonging to another operator (only base station Bis schematically shown in FIG. 5). Then, each of the base station A anda neighbor base station (such as the base station B) randomly oruniformly selects, in its coverage, a roadside unit or vehicle terminalsynchronized with the global synchronization signal source (that is,synchronized with the source vehicle SV) and registered with the sameoperator as the base station A or the neighbor base station, and theninstructs the roadside unit or vehicle terminal to act as an auxiliarynode device (shown as auxiliary node devices ADA and ADB in FIG. 4) totransmit synchronization information, as shown in steps S430 and S440.In addition, the base station A and the base station B transmit the roadevent-related information to the selected auxiliary node devices ADA andADB. Alternatively, the base station A and the base station B may selectspecific roadside units or vehicle terminals as the auxiliary nodedevices ADA and ADB within the broadcast range of the source vehicle SV.Subsequently, the selected auxiliary node devices ADA and ADB transmitthe synchronization information in steps S450 and S460, respectively. Inthis way, since there are a number of auxiliary node devices registeredwith different operators, a terminal of any target vehicle can quicklyestablish synchronization based on the synchronization information froman auxiliary node device which is registered with the same operator.

In the V2V communication, it is required that the road safetyinformation is quickly notified from the source vehicle SV to targetvehicles DV in the vicinity. Therefore, it is particularly important forthe source vehicle SV to quickly obtain a resource for broadcast. Theprocess where the communication terminal of the source vehicle SVacquires the resource for transmitting the road safety information fromthe serving base station of the communication terminal of the sourcevehicle SV is described below with reference to FIG. 5.

In the LTE-based V2V communication, a counterpart in communication witha vehicle communication terminal includes base station and anothervehicle terminal, and services of the vehicle communication terminalinclude conventional cellular service and short-range service whichrequires communication with another vehicle. The short-range servicegenerally includes a low-priority short-range service, such as normalD2D service which generally has a priority lower than that of a cellularservice, and a high-priority short-range service such as the road safetyevent described above. As to different types of services, the basestation allocates communication resource for the vehicle communicationterminal in different ways.

In a case where a road event (a high-priority short-range service)occurs, if the communication terminal of the source vehicle SV is in aRRC_IDLE state, the terminal of the source vehicle SV requests the basestation for a resource for transmitting the road safety informationthrough a random access procedure. The random access procedure is knownto those skilled in the art, and is not described here.

If the communication terminal of the source vehicle SV is in aRRC_CONNECTED state, the process of requesting resources further dependson whether the terminal has an uplink shared channel (UL-SCH) resource.A case where the terminal of the source vehicle SV does not have theUL-SCH resource is first described as following.

In this case, as shown in FIG. 5, the terminal of the source vehicle SVwaits for the next scheduling request (SR) period to apply forcommunication resource by reporting the SR, as shown in step S510.

Specifically, since the traditional period for SR report may be as longas 40 ms or even 80 ms, and the period for SR report of the terminalwould be very long as the terminals will be densely distributed in thefuture, it is necessary to take a time delay from generation of a highpriority short-range service to the report of SR into consideration.Assuming that the time delay is ΔT, and the maximum time delay allowedby the generated high-priority short-range service is T, the terminal ofthe source vehicle SV waits for the next period to report SR asdescribed above only in a case where ΔT<T. While in a case where ΔT>T,the communication terminal of the source vehicle SV applies for aresource for transmitting the road safety information through randomaccess procedure.

In addition, it should be noted that, maximum allowable time delays Tmay be set in advance for different high-priority short-range services.For example, the maximum allowable time delay T may be set to be thetime required to acquire a resource through the random access procedure.

In the conventional technology, a specific counter is set for reportingthe SR. Only in a case where the number of times for which the SR isreported exceeds a predetermined number, the random access procedure isperformed. Otherwise, the terminal continues to wait for the next periodto report the SR. The disadvantage of this mechanism when it is appliedto a cellular service and a low-priority short-range service is notapparent. However, when this mechanism is applied to the high-priorityshort-range service, it is often difficult to meet the requirement onthe time delay. For application to the high-priority short-rangeservice, a solution is possible, in which the vehicle terminal isdirectly configured with a period shorter than the conventional periodfor SR report. However, this solution has the following disadvantages:if the vehicle terminal handles only low-priority short-range services(of which the priority is lower than that of a cellular service),configuring a shorter period for SR report may lead to occupation ofcommunication resource, and thus the cellular service may be affected.In order to solve the problem, the present technology adopts a new SRreporting mechanism, which is described in detail below with referenceto FIG. 6.

When the terminal of the source vehicle SV initially accesses to thebase station, the base station may determine that the terminal is avehicle terminal through authentication. Therefore, the base station mayconfigure for the terminal of the source vehicle SV a short period forSR report, for example, a period which is a half of the period for SRreport of a common cellular terminal. During processing, the terminal ofthe source vehicle SV first identifies on the MAC layer whether theservice to be processed is a cellular service, a low-priorityshort-range service, or a high-priority short-range service, and thenautonomously selects appropriate period for SR report for differentservices. As shown in FIG. 6, for the cellular service, the vehicleterminal uses the same period for SR report as that of the commoncellular terminal. The period used for the low-priority short-rangeservice is 2 times that of the cellular service, and a report periodconfigured by the base station, which is a half of the period of thecellular service for example, is used for the high priority short rangeservice. It should be noted that the period configured by the basestation is the shortest period that can be used by the terminal of thesource vehicle SV for reporting the SR, that is, the terminal of thesource vehicle SV may report the SR with an appropriate periodicitywhich is selected in a range greater than or equal to the shortestperiod based on the type of service, which is expressed by the followingequation:(10*n _(f) +└n _(s)/2┘−N _(OFFSET,SR))mod(SR_(PERIODICITY)*Service_(priority))=0where n_(f) is system frame number, └n_(s)/2┘ indicates the number ofsubframe for transmitting the SR, N_(OFFSET,SR) indicates subframeoffset, SR_(PERIODICITY) indicates the available shortest periodconfigured by the base station, and Service_(priority) is a parameterindicating priority of service and may take a value of 1, 2, or 3 forexample. A higher priority may be indicated by a smaller value ofService_(priority).

With the above mechanism, the base station can easily determine a typeof a service of the vehicle terminal based on the period for SR report,so as to allocate a resource for the high-priority short-range servicein time and configure a longer period for SR report for the low-priorityshort-range service, to reduce the influence of competition forresources between the low-priority short-range service and the cellularservice.

Referring back to FIG. 5, the base station transmits an uplink grant (ULgrant) to the vehicle terminal in response to a scheduling request fromthe terminal of the source vehicle SV in step S520, where acommunication resource for reporting sidelink buffer status report (SLBSR) by the terminal of the source vehicle SV is indicated in the uplinkgrant. The SL BSR is described in detail below.

As described above, the services of the communication terminal of thevehicle include cellular service and short-range service, both of whichinvolve the scheduling request step (S510) and the UL grantconfiguration step (S520) described above. In an example of the presentdisclosure, the base station may simultaneously allocate a resource forreporting the SL BSR and a resource for broadcasting the road safetyinformation to the terminal of the source vehicle SV with the UL grantin step S520, regardless of whether the terminal of the source vehicleSV performs a high-priority short-range service or a cellular service.In this way, in a case where the terminal of the source vehicle SVperforms a high-priority short-range service (such as broadcast servicefor road safety information), the process may reduce at least a timeperiod of 4 ms for acquiring a resource for broadcasting the road safetyinformation, thereby reducing the time delay in applying for resources.In response to the UL grant, the terminal of the source vehicle SV maytransmit SL BSR in specific format (for example, with padded bits) instep S530 to indicate that the terminal has the broadcast service forroad safety information and uses the allocated resource for broadcast.On the contrary, if the terminal of the source vehicle SV does notperform the high-priority short-range service, the terminal reports anormal SL BSR in step S530, in which case the base station may releasethe resource for broadcast previously configured in the UL grant.

Specifically, since the above procedure occurs when the terminal is inthe RRC_CONNECTED state, the base station can determine whether theterminal initiating the scheduling request (SR) is a normal cellularcommunication terminal or a vehicle terminal by authentication. In acase where the terminal is a vehicle terminal, the above-describedspecial UL grant may be transmitted. While in a case where the terminalis a cellular communication terminal, the base station transmits theconventional UL grant, to reduce the influence of pre-configuration ofthe resource for broadcast.

Since the terminal of the source vehicle SV indicates only whether ithas information to transmit and does not indicate data amount of theinformation to be transmitted when requesting the resource from the basestation by reporting SR, the base station cannot determine the amount ofthe resource to be allocated for the terminal. Therefore, only theresource for further reporting the amount of information by the terminalis indicated in the UL grant. After obtaining the UL grant, the terminalfurther informs the base station of the amount of data to be transmittedin its buffer through SL BSR, so that the base station determines theamount of the communication resource to be allocated to the terminal, asdescribed in step S530. SL BSR reported by the terminal generallyincludes a group index, a logical channel group identifier (LCG ID) anda size of the corresponding buffer.

The group index is used for distinguishing communication groups, andobjects belonging to the same communication group can be identifiedthrough the group index. Generally, the group index is configured by abase station. However, in the V2V communication scenario, after theoccurrence of road event, a great time delay may be caused by the basestation configuring a group index for a communication group related tothe road event. In addition, it is unnecessary to distinguish thereceivers in the case of the broadcast of road safety information.Instead, all vehicles within the coverage of the broadcast signal canreceive the road safety information. Therefore, in an example of thepresent disclosure, the group index in SL BSR may be prescribed, forexample, may be fixedly set to “0000”.

Depending on the type of the service, the terminal may set up a greatnumber of radio bearers, each of which corresponds to a logical channel.If the terminal reports one SL BSR for each of logical channels, a largeamount of signaling overhead may be generated. To avoid this, multiplelogical channels are usually grouped into a logical channel group (LCG),and the terminal reports SL BSR on the basis of LCG instead of reportingSL BSR for each of the logical channels.

In the present disclosure, the road safety event is a high-priorityshort-range service and needs to preferentially obtain communicationresource after SL BSR is reported. Therefore, the identifier LCG ID ofthe logical channel group corresponding to the short-range service maybe set to “00”, to indicate that SL BSR regarding the short-rangeservice has a right to be reported preferentially. In contrast, the LCGID corresponding to the low-priority short-range service is generallyset to “11”.

It should be noted that setting the group index to “0000” and the LCG IDto “00” as described above is only exemplary, the present disclosure isnot limited to the specific values, and other values may also be used.The prescribed fixed group index and LCG ID may be used by the basestation to a certain degree to identify the SL BSR related to thehigh-priority short-range service, so that the base station maypreferentially configure communication resource for the terminal uponreceiving the SL BSR.

Then, the base station transmits a grant (specifically, sidelink (SL)grant) to the vehicle terminal in response to the SL BSR reported by theterminal of the source vehicle SV in step S540, where a communicationresource for broadcasting the road safety information by the terminal isindicated in the SL grant. Due to high requirement of the V2Vcommunication on reliability, the base station should preferentiallyallocate a dedicated frequency band resource for communicating the roadsafety information if such dedicated resource exists. In addition,licensed frequency bands and shared frequency bands (for example,auxiliary authorization access LAA) for the cellular service can also beconfigured for the broadcast of the road safety information.

The process in a case where the terminal of the source vehicle SV doesnot have UL-SCH resource is described above in steps S510 to S540. Theprocess in a case where the terminal has UL-SCH resource will bedescribed below. In a case where the terminal of the source vehicle SVhas UL-SCH resource, the process of acquiring the resource for broadcastfrom the base station includes only steps S530 and S540. That is, theterminal reports the SL BSR, and then the base station configures theresource for broadcast in response to the report and transmits the SLgrant.

With the transmission scheme of the road safety information according tothe first embodiment of the present disclosure, terminals of themultiple target vehicles DV1, DV2, . . . , DVn adjacent to the sourcevehicle SV can receive the road safety information correctly and timely,and thus the driver is provided with time to take action. Aninterruption process during transmission/reception of the road safetyinformation by the vehicle terminal is described below.

In a case where another synchronization information is detected when theterminal of the target vehicle DV is receiving the road safetyinformation, the terminal of the target vehicle DV determines, based onthe signal quality and the periodicity of the new synchronizationinformation, whether to continue to receive the current road safetyinformation or to synchronize with the new synchronization source toreceive new road safety information. Specifically, the terminal of thetarget vehicle DV first determines whether the reception quality of thenew synchronization information is higher than a predeterminedthreshold. In a case where the reception quality of the newsynchronization information is lower than the predetermined threshold,the terminal continues to receive the current road safety information.In a case where the reception quality of the new synchronizationinformation is higher than the predetermined threshold, the terminaldetermines, based on the transmission period of the new synchronizationinformation, whether a priority of a service corresponding to the newsynchronization information is higher than a priority of a servicecorresponding to the currently received road safety information. If theservice corresponding to the new synchronization information has ahigher priority, the terminal stops the current reception and starts tosynchronize with the new synchronization source to receive new servicemessage. Otherwise, the terminal continues the current reception.

Further, as shown in FIG. 7, if a new service is generated when theterminal of the source vehicle SV is transmitting the road safetyinformation, the terminal first determines in step S710 whether apriority of the new service is higher than a priority of a servicecorresponding to the currently transmitted road safety information. Ifthe priority of the new service is lower, the terminal continues tobroadcast the current road safety information in step S720. If thepriority of the new service is higher, the terminal suspends thebroadcast of the current road safety information in step S730 andnotifies the base station of this fact through SL BSR in step S740. Theterminal determines whether the resource previously allocated by thebase station for broadcasting the current road safety information issufficient to transmit the road safety information of the new service,as shown in step S750. If the resource is sufficient, the terminaltransmits the new road safety information by using the previouslyconfigured resource in step S760 without requesting the base station toallocate resources. Otherwise, the terminal re-requests a communicationresource from the base station in step S770 to transmit the new roadsafety information, and the base station may release the previouslyconfigured resource while reallocating resources. Optionally, aftertransmission of the new road safety information is finished, the basestation may reallocate the previously released resource to the terminalto continue the broadcast of the original road safety information.

The transmission of the road safety information according to the secondembodiment is described below with reference to FIG. 8. The secondembodiment mainly differs from the first embodiment in that the roadsafety information is broadcast to multiple target vehicles DV by thebase station instead of the source vehicle SV, so that target vehiclesin a wider range can be notified through one broadcast.

As shown in FIG. 8, the communication system to which the secondembodiment is applicable includes: a source vehicle SV, target vehiclesDVA and DVB (assuming that the target vehicles DVA and DVB are managedby base stations A and B of different operators, respectively), and acontroller which manages and controls the base station A and the basestation B.

After a road event occurs to the source vehicle SV, the terminal of thesource vehicle SV reports its location information and the generatedroad safety information to the base station A (herein, it is assumedthat the base station A is also the serving base station of the terminalof the source vehicle SV), as shown in step S810.

The base station A reports the received road safety information and thereceived location information of the source vehicle SV to the controllerin step S820, and broadcasts a paging message to all the vehicleterminals which are located in the coverage of the base station A andregistered with the same operator as the base station A in step S830 toindicate triggering of a road safety information broadcast (FIG. 8 onlyschematically shows that the paging message is transmitted to the targetvehicle DV A).

Then, the controller determines impact area of the road event based onthe received information, and transmits the received road safetyinformation to the base stations of respective operators within the areain step S840 (FIG. 8 only schematically shows that the received roadsafety information is transmitted to the base station B).

Upon receipt of the road safety information transmitted by thecontroller, the base station B starts the process for broadcasting theroad safety information, and broadcasts a paging message to all thevehicle terminals which are located within the coverage of the basestation B and registered with the same operator as the base station B instep S850 (FIG. 8 only schematically shows that the paging message istransmitted to the target vehicle DV B).

Then, in steps S860 and S870, the base station A and the base station Brespectively inform the target vehicles DVA and DVB managed by the basestation A and the base station B of the resources for broadcasting theroad safety information. For example, the base station A and the basestation B may indicate the resources by configuring SIB 18 (for example,commRxPool field), in which case the terminals of target vehicles DVAand DVB that receives the paging message may be informed of theresources for broadcasting the road safety information by monitoring SIB18, so as to receive the road safety information on the resources.

In an example, instead of the above steps S860 and S870, the basestation may also inform, with paging messages, all the terminals of thetarget vehicles DV in RRC_IDLE state to establish connections with thebase station, and then notify these terminals of the resource forbroadcasting the road safety information in unicast. This manner is moresuitable for a scenario where there are fewer vehicles on the road,otherwise, a great time delay may be caused.

Finally, in steps S880 and S890, the base station A and the base stationB broadcast the road safety information to the target vehicles DVA andDVB, respectively. In an example, the coverage of the base station isusually large and may be beyond the impact area of the occurred roadevent. In this case, in order to avoid unnecessary operations ofirrelevant vehicles, the base station may include the locationinformation of the source vehicle SV in the broadcast information, sothat only vehicles within a certain distance from the source vehicle SVneed to receive the road safety information.

The advantage of the scheme where the road safety information isbroadcast by the base station as described in the second embodiment isapparent. The base stations of respective operators are responsible fornotifying the road safety information to the vehicle terminals which arelocated within the impact area of the event and registered with the sameoperator as the base station, thereby avoiding synchronization andinformation transmission among the vehicle terminals registered withdifferent operators. Therefore, the process is simplified.

Various embodiments of the present disclosure are described above indetail with reference to the accompanying drawings. It is providedaccording to the present disclosure a solution for reliably and rapidlyacquiring communication resource, establishing synchronization andtransmitting road safety information in a V2V communication system. Thesolution is especially suitable for a scenario where multiple operatorscoexist. That is, synchronization can be rapidly establish and roadsafety information can be transmitted among the vehicle terminalsregistered with different operators.

The base station described in the present disclosure may be realized asany type of evolved Node B (eNB) such as macro eNB and small eNB. Thesmall eNB may be an eNB such as pico eNB, micro eNB and home (femto) eNBthat covers a cell smaller than a macro cell. Instead, the base stationmay be realized as any other types of base stations such as NodeB andbase transceiver station (BTS). In addition, various types of terminalsdescribed below may each operate as the base station by temporarily orsemi-persistently implementing the function of a base station. The basestation may include a main body (that is also referred to as basestation device) configured to control radio communication, and one ormore remote radio heads (RRH) provided separately from the main body.

The execution sequence of the steps described herein is merelyillustrative and does not limit the order in which the processes orflows may be performed. Without affecting the implementation of thepresent disclosure, the execution sequence of the steps may be changed,or some steps may be performed in parallel with other steps. Forexample, steps S830 and S850 in FIG. 8 may be performed simultaneously,instead of being performed in the order as shown in the figure. Thisalso applies to steps S860 and S870, and steps S880 and S890.

The various devices or modules described herein are only in the logicalsense and do not strictly correspond to any physical devices orentities. For example, the function of each module described herein maybe implemented by multiple physical entities, or the functions ofmultiple modules described herein may be implemented by a singlephysical entity. In addition, the features, components, elements, steps,and the like described in one embodiment are not limited to theembodiment, but may also be applied to other embodiments, for example,by replacing specific features, components, elements, and steps in theother embodiments or combining with the specific features, components,elements, and steps in the other embodiments.

The series of processes executed by each device or module in theabove-described embodiments may be implemented by software, hardware, ora combination of the software and the hardware. Programs included in thesoftware may be stored in advance in a storage medium provided inside oroutside each device. As an example, during execution, these programs arewritten to a random access memory (RAM) and executed by a processor (forexample, a CPU).

FIG. 9 is a block diagram showing an exemplary configuration of computerhardware that executes the above-described processes according to aprogram.

In computer 900, central processing unit (CPU) 901, read only memory(ROM) 902, and random access memory (RAM) 903 are connected to eachother by bus 904.

The input/output interface 905 is further connected to the bus 904. Theinput/output interface 905 is connected with the following components:input unit 906 including keyboard, mouse, microphone and the like;output unit 907 including display, speaker and the like; storage unit908 including hard disk, nonvolatile memory and the like; communicationunit 909 including network interface card (such as local area network(LAN) card, modem); and drive 910 driving removable medium 911 such asmagnetic disk, optical disk, magneto-optical disk or semiconductormemory.

In the computer having the above configuration, the CPU 901 loads theprogram stored in the storage unit 908 into the RAM 903 via theinput/output interface 905 and the bus 904 and executes the program, toexecute the above-described processes.

A program to be executed by a computer (the CPU 901) may be recorded onthe removable medium 911 which is a package medium including, forexample, magnetic disk (including floppy disk), optical disk (includingcompact disk-read only memory (CD-ROM), digital versatile disk (DVD) andthe like), magneto-optical disk or semiconductor memory. In addition,the program to be executed by the computer (the CPU 901) may also beprovided via a wired or wireless transmission medium such as local areanetwork, the internet or digital satellite broadcasting.

In a case where the removable medium 911 is installed in the drive 910,the program may be installed in the storage unit 908 via theinput/output interface 905. In addition, the program may be received bythe communication unit 909 via a wired or wireless transmission medium,and the program may be installed in the storage unit 908. Alternatively,the program may be installed in the ROM 902 or the storage unit 908 inadvance.

The program to be executed by the computer may be a program thatexecutes the processes in the order described in the presentspecification, or may be a program that executes the processes inparallel or executes the process when needed (such as when called).

The embodiments and the technical effects of the present disclosure aredescribed in detail above with reference to the accompanying drawings,but the scope of the present disclosure is not limited thereto. It is tobe understood by those skilled in the art that various modifications orchanges can be made to the embodiments described herein withoutdeparting from the spirit and scope of the present disclosure dependingon design requirements and other factors. The scope of the presentdisclosure is defined by the appended claims or their equivalents.

In addition, the present disclosure may also be configured as follows.

A node device for vehicle-to-vehicle communication, which includes oneor more processors configured to: perform control, in response to roadevent-related information from a source device, to establish timesynchronization with the source device; and generate synchronizationinformation for transmission to one or more target devices, so that thetarget devices establish time synchronization with the source devicebased on the synchronization information, wherein the node device is aroadside unit or an onboard device capable of communication.

The one or more processors are further configured to perform control toestablish time synchronization with the source device according to aglobal synchronization signal source.

The node device and the source device are registered with differentoperators, and the node device and the target device are registered withthe same operator.

The one or more processors are further configured to: determine apriority of the road event based on the road event-related information;and determine a transmission period for the synchronization informationbased on the priority, wherein the higher the priority is, the shorterthe transmission period is.

A resource for transmitting the synchronization information isprescribed and indicated to the node device and the target devices inadvance. The synchronization information is transmitted by using adedicated signaling.

A method for performing synchronization in a vehicle-to-vehiclecommunication system, which includes: establishing, by a node device,time synchronization with a source device, in response to roadevent-related information from the source device; transmitting, by thenode device, synchronization information to one or more target devices;and establishing, by the target devices, time synchronization with thesource device based on the received synchronization information, whereinthe node device is a roadside unit or an onboard device capable ofcommunication.

The node device establishes time synchronization with the source deviceaccording to a global synchronization signal source.

The node device and the source device are registered with differentoperators, and the node device and the target devices are registeredwith the same operator.

The method further includes: transmitting, by the source device,location information of the source device and the road event-relatedinformation to a serving base station of the source device; informing,by the serving base station of the source device, one or more neighborbase stations of the location information and the road event-relatedinformation; and selecting, by each of the serving base station and theone or more neighbor base stations, a communication devices which islocated within its coverage and registered with the same operator as itis, as the node device, and transmitting, by each of the serving basestation and the one or more neighbor base stations, the roadevent-related information to the selected node device, wherein theserving base station and the one or more neighbor base stations areregistered with different operators.

The method further includes: each of the serving base station and theone or more neighbor base stations selects the node device within apredetermined distance from the source device in its coverage.

The node devices selected by the serving base station and by theneighbor base stations are registered with different operators.

The method further includes: establishing, by a specific target deviceamong the one or more target devices, time synchronization with thesource device based on synchronization information from another nodedevice in a case where the specific target device is out ofsynchronization with the source device.

The method further includes: determining, by the target device, whetherto establish a new synchronization based on quality and transmissionperiod of new synchronization information upon receipt of the newsynchronization information.

A device for vehicle-to-vehicle communication, which includes one ormore processors configured to: generate a request message for requestinga base station to allocate a resource; perform control to establish timesynchronization with a node device, such that at least one targetdevices establish time synchronization with the device based onsynchronization information transmitted by the node device, wherein thenode device is a roadside unit or an onboard device capable ofcommunication; generate a control message for informing the at least onetarget devices of the resource allocated by the base station; andgenerate service information related to a service for transmission tothe at least one target devices via the resource allocated by the basestation.

The one or more processors are further configured to: generate a firstrequest message for transmission to the base station, wherein the firstrequest message is used for requesting the base station to allocate aresource for transmitting a second request message; and generate thesecond request message for transmission to the base station, wherein thesecond request message is used for requesting the base station toallocate a resource for transmitting the service information, whereinthe control information is used for informing the at least one targetdevices of the resource for transmitting the service information.

The one or more processors are further configured to generate the secondrequest message in a specific format, in a case where the base stationsimultaneously allocates the resource for transmitting the secondrequest message and the resource for transmitting the serviceinformation in response to the first request information.

At least one of a service identifier and a group index in the secondrequest message is fixed.

The one or more processors are further configured to determine, whentransmitting the service information related to the service, whether torequest the base station to allocate a resource for transmitting serviceinformation related to a new service based on a priority of the newservice.

The one or more processors are further configured to generate a requestmessage for requesting the base station to allocate a resource, in acase where the priority of the new service is higher than the priorityof the service and the resource which has been allocated by the basestation is insufficient to transmit the service information related tothe new service.

The one or more processors are further configured to perform control toestablish time synchronization with the node device according to aglobal synchronization signal source.

The node device and the device are registered with different operators,and the node device and the target devices are registered with the sameoperator.

The service information is road safety service information.

A method for transmitting service information in a vehicle-to-vehiclecommunication system, which includes: transmitting, by a source device,a request message to a base station, wherein the request message is usedfor requesting the base station to allocate a resource; transmitting, bya node device in synchronization with the source device, synchronizationinformation to at least one target devices, such that the at least onetarget devices establish time synchronization with the source devicebased on the synchronization information, wherein the node device is aroadside unit or an onboard apparatus capable of communication;informing, by the source device, the at least one target devices of theresource allocated by the base station; and transmitting, by the sourcedevice, the service information to the at least one target devices byusing the resource.

The step of transmitting the request message includes: transmitting afirst request message, wherein the first request message is used forrequesting the base station to allocate a resource for transmitting asecond request message; transmitting the second request message by usingthe resource for transmitting the second request message allocated bythe base station, wherein the second request message is used forrequesting the base station to allocate a resource for transmitting theservice information, wherein the source device informs the at least onetarget devices of the resource for transmitting the service information,so as to transmit the service information to the at least one targetdevices.

The method further includes: simultaneously allocating, by the basestation, both the resource for transmitting the second request messageand the resource for transmitting the service information to the sourcedevice, in response to the first request message.

The node device and the source device are registered with differentoperators, and the node device and the target devices are registeredwith the same operator.

A method for transmitting service information in a vehicle-to-vehiclecommunication system, wherein the vehicle-to-vehicle communicationsystem includes multiple base stations, a controller for controlling themultiple base stations, a source device, and at least one targetdevices, and the method includes: acquiring, by the controller, locationinformation and service information of the source device from a servingbase station of the source device; transmitting, by the controller, theservice information to all neighbor base stations within a predeterminedrange around the source device; and broadcasting, by each of theneighbor base stations, the service information to the target devicewithin its coverage.

The multiple base stations are registered with different operators, andeach of the neighbor base stations broadcasts the service information tothe target device which is located within its coverage and registeredwith the same operator as it is.

Only the target device located within a predetermined distance from thesource device receives the service information.

The invention claimed is:
 1. A node device for vehicle-to-vehiclecommunication, comprising circuitry configured to: receive roadevent-related information from a source device that is in timesynchronization with the node device; determine a transmission periodfor synchronization information based on a priority of the roadevent-related information; and transmit the synchronization informationto a target device in the determined transmission period, therebyenabling the target device to establish time synchronization with thesource device based on the synchronization information, wherein thesynchronization information comprises a sidelink synchronization signal(SLSS) and a master information block-sidelink (MIB-SL), and wherein thenode device is an auxiliary node device configured to communicatewirelessly with the source device.
 2. The node device of claim 1,wherein a transmission period for the synchronization information is 20ms or less.
 3. The node device of claim 1, wherein the determinedtransmission period is between 20 ms and 40 ms.
 4. The node device ofclaim 1, wherein the synchronization information is transmitted throughdedicated signaling.
 5. The node device of claim 1, wherein anidentifier of the synchronization information is limited to a part of167 identifiers used in device-to-device communication.
 6. The nodedevice of claim 1, wherein a network type and a cyclic prefix type of asignal used to transmit the synchronization information is prescribed.7. The node device of claim 1, wherein a modulation and coding scheme ofa signal used to transmit the road event-related information areprescribed.
 8. The node device of claim 1, wherein the circuitry isfurther configured to receive an instruction from a base station totransmit the synchronization information to a vehicle that is out ofsynchronization.
 9. The node device of claim 1, wherein the sourcedevice is a first vehicle, the target device is a second vehicle, andthe road event-related information comprises safety information.
 10. Thenode device of claim 1, wherein the circuitry is further configured totransmit the synchronization information in response to receiving aninstruction from a base station, wherein the base station selects thenode device in response to a request from the source device to allocatea resource for communicating the road event-related information.
 11. Thenode device of claim 1, wherein different transmission periods for thesynchronization information are determined for different priorities ofthe road event-related information.
 12. A method for vehicle-to-vehiclecommunication, comprising: receiving at a node device road event-relatedinformation from a source device that is in time synchronization withthe node device; determining a transmission period for synchronizationinformation based on a priority of the road event-related information;and transmitting, by the node device, the synchronization information toa target device in the determined transmission period, thereby enablingthe target device to establish time synchronization with the sourcedevice based on the synchronization information, wherein thesynchronization information comprises a sidelink synchronization signal(SLSS) and a master information block-sidelink (MIB-SL), and wherein thenode device is an auxiliary node device configured to communicatewirelessly with the source device.
 13. The method of claim 12, wherein atransmission period for the synchronization information is 20 ms orless.
 14. The method of claim 12, wherein the determined transmissionperiod is between 20 ms and 40 ms.
 15. The method of claim 12, whereinthe synchronization information is transmitted through dedicatedsignaling.
 16. The method of claim 12, wherein an identifier of thesynchronization information is limited to a part of 167 identifiers usedin device-to-device communication.
 17. The method of claim 12, wherein anetwork type and a cyclic prefix type of a signal used to transmit thesynchronization information is prescribed.
 18. The method of claim 12,wherein a modulation and coding scheme of a signal used to transmit theroad event-related information are prescribed.
 19. The method of claim12, further comprising: receiving an instruction from a base station totransmit the synchronization information to a vehicle that is out ofsynchronization.